Low temperature thin films formed from nanocrystal precursors

Abstract

Nanocrystals of semiconductor compounds are produced. When they are applied as a contiguous layer onto a substrate and heated they fuse into a continuous layer at temperatures as much as 250, 500, 750 or even 1000° K below their bulk melting point. This allows continuous semiconductor films in the 0.25 to 25 nm thickness range to be formed with minimal thermal exposure.

What is claimed is: 
     
       1. A process for forming a solid continuous thin film of a semiconductor material on a solid support surface comprising the steps of (a) depositing on the solid support surface a thin contiguous layer of nanocrystals of the semiconductor material,   (b) exposing the nanocrystals to a temperature which is not greater than 250° K below the bulk melting point of the semiconductor material, which temperature nonetheless is adequate to melt the nanocrystals and cause them to fuse into a continuous thin film, and   (c) cooling the continuous thin film to yield a solid continuous thin film.   
     
     
       2. The process of claim 1 wherein the nanocrystals have an average diameter of from 1 to about 6 nm. 
     
     
       3. The process of claim 2 wherein the semiconductor is a II-VI material. 
     
     
       4. The process of claim 2 wherein the semiconductor is a III-V material. 
     
     
       5. The process of claim 2 wherein the temperature is not greater than 500° K below the bulk melting point of the semiconductor material. 
     
     
       6. The process of claim 2 wherein the semiconductor is GaAs. 
     
     
       7. The process of claim 2 wherein the semiconductor is CdS.